8849 Tank 2 Pro by Unihertz Review - the current battery life champion

Battery Tests

8849 Tank 2 Pro by Unihertz uses a 23800 mAh Li-Pol battery pack. The nominal battery voltage is 3.87V x 2 = 7.74V (double parallel and double series form), while the maximum one is 4.45V x 2= 8.9V. To help the charging process, the device has an onboard independent coulomb meter with model name Zhongying SH366003. The smartphone arrives with a 120W fast charger pictured above. 10W reversed wired charging is also supported and you can use the Tank 2 Pro as a reliable power bank that can make phone calls, browse the internet, and serve as a camera at the same time. All battery tests we run on the devices we review are developed by us and performed with the screen of the device being calibrated to 200 cd/m². Battery-saving features are disabled. The battery of our review unit charged in full for 2 hours and 9 minutes. The charging process is very fast during the first 22 minutes, which regains 40% of the battery charge. After that, the process slows down and the battery regains its charge up to 90% for the next 1 hour. The third stage is from 90% to 100% during which the charging process slows down even more and it takes 47 minutes. The battery temperature begins at 27°C, reaches 45°C in 22 minutes, and peaks at 47°C after another 20 minutes. The temperature starts decreasing 15 minutes later and at the end measures 35°C. During our intensive browsing test with the screen's refresh rate set at 60Hz, the battery lasted for 64 hours and 33 minutes. This is the top result in this particular battery life test. The discharging process is stable from the start almost until the end - at 3% the device shuts down. The battery temperature starts at 27°C and after 1 hour, it goes up to 29°C, remains there for 6 hours, and then drops back to 27°C, remaining at this level until the end. During our intensive browsing test with the screen's refresh rate set at 120Hz, the battery lasted for 54 hours and 35 minutes making it again the No1 model in battery stamina. The discharging process closely follows the pattern from the browsing test at 60Hz but this time the device shuts off when the battery drops to 5% of its charge. The battery temperature starts at 29°C, reaches 34°C in 18 hours, and fluctuates between 32-33°C until the end. The video test for battery life uses a 1080p video at 30 fps with a ~20Mbps rate is used. Our review unit's score is 66 hours and 36 minutes. It beats by two hours the result of the Tank 3 Pro and now the Tank 2 Pro is the No2 device in this battery life test. The discharging process develops in relatively the same way. The battery temperature starts at 28°C, goes up to 33°C after 3 hours, drops to 30°C after 5 hours, and continues fluctuating like this until the end when it measures 30°C. The 4K video battery life test uses a 2160p video at 30 fps with a ~55 Mbps rate. In this test, the battery of the Tank 2 Pro lasted for 57 hours. This result beats the Tank 3 Pro by 36 minutes and is the top result in this test from all smartphones we've tested so far. The discharging process graph shows that the process develops steadily and the device switches off when the battery charge drops to 3%. The battery temperature fluctuates between 31°C and 33°C from the start until the end. For the 3D Graphics/Gaming test, Real Racing 3 is used. The result from this test is 40 hours and 54 minutes. The Tank 2 Pro excels in this test, too, and steals off the first place from its sibling - the Tank 3 Pro. The discharging process curve shows a faster-discharging momentum after the battery's charge drops below 3%. The battery temperature starts at 30°C, reaches 35°C in 5 hours, and fluctuates between 35°C and 36°C for the next 23 hours. Then, it increases the range to 37-38°C maintaining this level until the end. The above photos of the Tank 2 Pro are taken with a FLIR thermal camera. The upper photo shows the device's temperature during charging. The hottest part is the bottom half of the body with three reference points - the left frame, the middle, and the right frame with temperatures of 45.1°C, 45°C, and 44.9°C, respectively. The second photo depicts the device's temperature during our 3D battery life test. In this case, the hottest part is the center of the chin with a temperature of 41.1°C.

Battery Settings

The Battery menu is as standard as possible. It provides information about the battery's current status and usage - by app and hardware. The standard Battery Saver feature is here as well with options for scheduling and automatic turning off. A toggle for showing the battery percentage in the status bar is also provided. We've also included two screenshots from the battery management options for each application - these can be accessed from the Apps menu in the Settings.